Scanning transmission X-ray microscopy

Scanning transmission X-ray microscopy (STXM) is a type of X-ray microscopy in which a zone plate focuses an X-ray beam onto a small spot, a sample is scanned in the focal plane of the zone plate and the transmitted X-ray intensity is recorded as a function of the sample position. A stroboscopic scheme is used where the excitation is the pump and the synchrotron X-ray flashes are the probe. X-ray microscopes work by exposing a film or charged coupled device detector to detect X-rays that pass through the specimen. The image formed is of a thin section of specimen. Newer X-ray microscopes use X-ray absorption spectroscopy to heterogeneous materials at high spatial resolution. The essence of the technique is a combination of spectromicroscopy, imaging with spectral sensitivity, and microspectroscopy, recording spectra from very small spots.